Re: [PATCH V6 03/15] mmc: core: Add support for re-tuning before each request

Adrian Hunter
2015-05-06T08:04:53Z

On 04/05/15 16:28, Ulf Hansson wrote:
> On 20 April 2015 at 14:09, Adrian Hunter <adrian.hunter@intel.com> wrote:
>> At the start of each request, re-tune if needed and
>> then hold off re-tuning again until the request is done.
>>
>> Note that though there is one function that starts
>> requests (mmc_start_request) there are two that wait for
>> the request to be done (mmc_wait_for_req_done and
>> mmc_wait_for_data_req_done). Also note that
>> mmc_wait_for_data_req_done can return even when the
>> request is not done (which allows the block driver
>> to prepare a newly arrived request while still
>> waiting for the previous request).
>>
>> This patch ensures re-tuning is held for the duration
>> of a request. Subsequent patches will also hold
>> re-tuning at other times when it might cause a
>> conflict.
>>
>> Signed-off-by: Adrian Hunter <adrian.hunter@intel.com>
>
> Patch2 is calling mmc_retune_needed() and thus actually triggers a
> re-tune to potentially happen.

That won't happen because host->retune_period is not set, so
mmc_retune_needed() won't be called.

>
> To avoid bisectability issues about not holding re-tune when needed, I
> suggest we move $subject patch to after patch8.
>
> Kind regards
> Uffe
>
>> ---
>> drivers/mmc/core/core.c | 32 +++++++++++++++++++++++++-------
>> 1 file changed, 25 insertions(+), 7 deletions(-)
>>
>> diff --git a/drivers/mmc/core/core.c b/drivers/mmc/core/core.c
>> index dd43f9b..a9936cb 100644
>> --- a/drivers/mmc/core/core.c
>> +++ b/drivers/mmc/core/core.c
>> @@ -186,12 +186,29 @@ void mmc_request_done(struct mmc_host *host, struct mmc_request *mrq)
>>
>> EXPORT_SYMBOL(mmc_request_done);
>>
>> +static void __mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
>> +{
>> + int err;
>> +
>> + /* Assumes host controller has been runtime resumed by mmc_claim_host */
>> + err = mmc_retune(host);
>> + if (err) {
>> + mrq->cmd->error = err;
>> + mmc_request_done(host, mrq);
>> + return;
>> + }
>> +
>> + host->ops->request(host, mrq);
>> +}
>> +
>> static int mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
>> {
>> #ifdef CONFIG_MMC_DEBUG
>> unsigned int i, sz;
>> struct scatterlist *sg;
>> #endif
>> + mmc_retune_hold(host);
>> +
>> if (mmc_card_removed(host->card))
>> return -ENOMEDIUM;
>>
>> @@ -252,7 +269,7 @@ static int mmc_start_request(struct mmc_host *host, struct mmc_request *mrq)
>> }
>> mmc_host_clk_hold(host);
>> led_trigger_event(host->led, LED_FULL);
>> - host->ops->request(host, mrq);
>> + __mmc_start_request(host, mrq);
>>
>> return 0;
>> }
>> @@ -422,17 +439,16 @@ static int mmc_wait_for_data_req_done(struct mmc_host *host,
>> cmd->opcode, cmd->error);
>> cmd->retries--;
>> cmd->error = 0;
>> - host->ops->request(host, mrq);
>> + __mmc_start_request(host, mrq);
>> continue; /* wait for done/new event again */
>> }
>> } else if (context_info->is_new_req) {
>> context_info->is_new_req = false;
>> - if (!next_req) {
>> - err = MMC_BLK_NEW_REQUEST;
>> - break; /* return err */
>> - }
>> + if (!next_req)
>> + return MMC_BLK_NEW_REQUEST;
>> }
>> }
>> + mmc_retune_release(host);
>> return err;
>> }
>>
>> @@ -471,8 +487,10 @@ static void mmc_wait_for_req_done(struct mmc_host *host,
>> mmc_hostname(host), cmd->opcode, cmd->error);
>> cmd->retries--;
>> cmd->error = 0;
>> - host->ops->request(host, mrq);
>> + __mmc_start_request(host, mrq);
>> }
>> +
>> + mmc_retune_release(host);
>> }
>>
>> /**
>> --
>> 1.9.1
>>
>> --
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>
>